(a) Field of the Invention
The invention relates to a pick-up apparatus and a pick-up method and, more particularly, to a pick-up apparatus which is used in a mounting step in the manufacture of semiconductor devices, and a pick-up method used during a mounting operation of semiconductor devices.
(b) Description of the Related Art
In a mounting step during the manufacture of semiconductor devices, a plurality of semiconductor pellets or chips disposed in an aligned arrangement as divided from a semiconductor wafer is subjected to an image recognition in order to allow non-faulty chips to be picked up for mounting.
Specifically, a plurality of chips disposed in an aligned arrangement are viewed one by one by a camera, and chips disposed within a field of view of the camera are subjected to an image processing operation. In the image processing operation, image data for the chip location obtained on the basis of the image signal from the camera is stored in a frame memory, and an image recognition is applied based on the image data in order to examine if the chip (or chip location) is faulty or non-faulty. A decision to examine and determine whether a chip location is faulty or non-faulty is executed by determining the presence or absence of the chip itself at the chip location, the presence or absence of any fault in the appearance such as a notch on the chip surface, and the presence or absence of a faulty mark which may be applied to the chip surface based on the results of a previous test for electric characteristics of the chip. After the image recognition, only a chip which is determined to be non-faulty is picked up by a devoted jig, called a "collet", which applies a vacuum suction to the chip. The picked up chip is then mounted on an island or die pad of a lead frame.
In the prior art practice, as illustrated in FIG. 1, a chip 10 is subjected to an image recognition within a field of view 11 of a camera, and the operation which sequentially picks up non-faulty chips is executed in accordance with timing charts shown in FIGS. 2A and 2B.
FIG. 2A illustrates an example of a pick-up operation in which all the subject chips shown in FIG. 1 are non-faulty. In this instance, a first chip located within the field of view of the camera is subjected to an image recognition (step S1), and positioned at the pick-up position, e.g, at the center of the field of image of the camera (step S2). Upon completion of the positioning of the chip, the chip is picked up by the collet (step S3). After the pick-up operation thereof is completed, a second chip is moved by a one pitch movement into the field of view (step S4). Subsequently, the second chip located within the field of view is subjected to an image recognition (step S5), then positioned at the pick-up position (step S6) and picked up in a manner similar to that as described above. The described operations are repeated to pick up successive chips arranged in a matrix.
FIG. 2B illustrates another example of a pick-up operation in which a first and a third chips are faulty while a second chip is non-faulty. In this instance, the first chip is subjected to an image recognition within the field of view (step S11), where the first chip is determined to be faulty based on the image recognition, and accordingly, the pick-up operation thereof is not executed. A one-pitch movement occurs instead for the second chip (step S12), which is then subjected to an image recognition in the field of view of the camera (step S13), and is determined to be non-faulty. As a result, the second chip is positioned at the pick-up position (step S14) and then picked up (step S15). Upon completion of the pick-up operation, one pitch movement further takes place for the third chip (step S16), which is then subjected to an image recognition in the field of view (step S17) and determined to be faulty. Subsequently, a further one pitch movement occurs for the next succeeding chip (step S18), thus repeating the described operations.
It will be noted that in the above-described pick-up method, a chip located within the field of view of the camera is subjected to an image recognition, then positioned at the pick-up position, and finally picked up upon completion of the positioning. After completion of the pick-up operation for a chip, a one pitch movement takes place for a next chip, which is again subjected to a sequence of an image recognition, positioning and pick-up operation thereof in a similar manner.